Does my sister's mother have right to any belongings since my sister is a minor or is this strictly between me and my sister?

If Will did not appoint guardian or trustee, she may have control as the parent.

Where did your father live at the time of his death? Did he have a will? Who is the personal representative? Minors cannot own land or hold money. If your father planned ahead and made a will or trust then he would have provided that if your sister was a minor then her share of the inheritance would be placed in trust for her. If your father had no will and if this is in North Carolina, then any surviving spouse (if your father remarried) and your father's biological/adopted children would inherit his share. However, this assumes that your father had probate assets. Not all all assets are probate assets - joint checking accounts, land owned jointly with another with right of survivorship/tenancy-by-the-entireties, life insurance or another beneficiary designated asset all pass outside probate. Since your father was divorced, the mother of your sister has no rights to anything unless there was a will that specifically made some provision for her following the divorce. Divorce revokes any provisions in favor of a spouse in a will. If there is no will and if your father did not have a living spouse to whom he was married, then his assets would pass to your, your minor sister and any other siblings. If there are only you and your sister, then you split. Since minors cannot hold property, then a guardian must be appointed for your sister and the guardian has to be bonded unless the sum of money is very small - about $1500. If there is no guardian, then your sister's share of the probate assets would be paid to the clerk of court to be held until your sister turns 18. I do not know what your father owned other than money. If the personal items are small (like photos or a coin collection), these things probably can be given to her now. I suggest that you, if you are the personal representative, consul with a probate attorney in the county/state where your father lived at the time of his death. My answers are premised on NC law only as that is where I am admitted. Each state has different probate requirements and the rules for a minor inheriting any property may differ.

You have not given us all the relevant facts, such as whether there is a Will, who are named the heirs and to what extent, etc. If your parents wee divorced then your mother would not be entitled to anything not covered in the divorce papers. Your mother could still be your sister's personal guardian ad litem but that does not give her any right to the property, just control over it until your sister is no longer a minor.

I take it your father had no will. In that case, his estate is divided 50% to his spouse, and 50% to his children in equal shares. If he had no wife when he passed away, then equally to his children. The fact that one child is a minor doesn't matter, although she may need some adult to hold property for her.

Not enough facts, to give you a suggested solution. Suggest you contact a probate lawyer for a consultation, and be prepared to pay for his time and advice.

See an attorney but if there is no will it would appear it is between your sister and yourself.

No, but minors can not directly control assets so she may be involved as a custodian if no one else can do it.

Assuming your father left no will, his estate goes equally to his children. Because your sister is a minor, her mother probably can act on her behalf.

The ex-step-mother does not have any rights to the estate. Since there is no spouse, the estate is divided equally between the children. If there are minor beneficiaries, their share is put in trust until they turn 18 years old.

Your sister's minority will not prevent her from inheriting anything. She would be entitled to the same share that you would.